The present invention relates to an apparatus for everting and curing a flexible tube as a liner in the interior of a hollow tubular conduit, such as a previously existing underground sewer pipe.
One of the more successful pipe repair or rehabilitation processes which is currently used is described in Wood, U.S. Pat. No. 4,064,211. Wood, U.S. Pat. No. 4,385,885 discloses apparatus useful in installing a liner according to the process described in U.S. Pat. No. 4,064,211, and briefly mentions, but does not describe, a lip seal, used in conjunction with a pair of controlled rollers to feed a liner into a conduit that is to be repaired. Various other sealing devices have been disclosed for use in connection with using fluid under pressure to evert a liner and extend it into a conduit to be repaired, as shown, for example, in Alexander, Jr., U.S. Pat. Nos. 5,597,353 and 5,942,183, Long, Jr., U.S. Pat. No. 5,358,359, Driver, et al., U.S. Pat. Nos. 5,154,936 and Re. 35,944.
Other apparatus for use in installing and everting a liner, as disclosed in Long, Jr., U.S. Pat. Nos. 4,668,125 and 4,685,983, has been quite large, and has avoided the use of a seal to maintain pressure within a portion of an apparatus by instead using a relatively tall column of water to provide the necessary fluid pressure within the liner being everted.
Such apparatus has been undesirably unwieldy and expensive. Because of its size, such apparatus is difficult or even dangerous to use in residential areas where fences obstruct access to conduits in need of repair, and such tall support apparatus presents a risk of inadvertent contact with electric power lines. Additionally, the weight of some such apparatus, particularly when filled with water, makes its use difficult wherein there is no paved surface near the point of access to the conduit to be repaired.
The need to ensure stability of such tall and heavy apparatus also presents some concerns that it is desired to avoid.
For installation of lines in relatively small and short conduits in some cases an entire prepared liner has been stacked inside a closed container, such as a special truck body, and the liner has been everted directly from within the truck. This method, however, presents difficulty in assuring that a liner is extended and everted smoothly and requires a container of special construction to contain and withstand the force of the pressurized fluid needed to extend and evert the liner tube.
What is desired, then, is to provide a system including conveniently small, safe, and relatively inexpensive apparatus useful to evert and install a flexible tubular liner into a conduit quickly and efficiently.